With recent rapid increase in demand for mobile communication, there is an increasing demand for global roaming capable of communication using the same number everywhere in the world, and accordingly, an international roaming service using a smart card such as SIM (Subscriber Identity Module), UIM (User Identity Module) or USIM (Universal Subscriber Identity Module) is provided.
SIM, as a smart card module inserted into an European wireless communication (GSM (Global System for Mobile communication)) type terminal for certification of a mobile communication network, complies with ISO (International Organization for Standardization) 7816, and is capable of storage of non-volatile data such as a telephone directory or a wireless communication service provider information, encoding, and execution of software. And, a SIM card contains a telephone number, a personal security key or data necessary to operate a mobile terminal, and after the SIM card is separated from a mobile terminal in use and mounted in a new mobile terminal, communication is possible by the new mobile terminal.
UIM, as a smart card module according to ISO 7816, is inserted into a multimode terminal of CDMA (Code Division Multiple Access) and European wireless communication (GSM), and supports certification and roaming functions. A UIM card is a kind of CDMA SIM card.
USIM, as a smart card module according to ISO 7816, is inserted into a third-generation wireless terminal, and provides network certification and an additional function, and a USIM card is standardized to mount at least 64 KB EEPROM (Electrically Erasable Programmable Read Only Memory).
To make an international call with a mobile terminal, first a user inputs an international call recognition number or an international telephone number recognition number (for example, 001, 002, 00345 and so on), a country number and a telephone number except “0” in sequence. In the case that the user does not know an international call recognition number or the user wants to use an international call recognition number provided as a default by a mobile service provider, the user may request an international call by inputting a plus “+” sign into a start of a telephone number. The plus “+” sign is displayed by continuously inputting a star “*” sign or long pressing a numeric key “0” with a general GSM terminal.
The same is the case that a user makes an international call using a telephone directory stored in a memory of a mobile terminal or a memory of a smart card module (SIM, UIM or USIM). That is, if the user does not input a plus “+” sign into a start of a telephone number when storing the telephone number into a telephone directory, TON (Type Of Number) of the telephone number is stored as “Unknown”, and if the user inputs a plus “+” sign, TON of the telephone number is stored as “INT (International)”. Thus, judgment can be made whether an incoming call is an international call or not by the TON in a mobile communication network. Here, “Unknown” is an indicator system, by which a mobile terminal or a mobile switching center (MSC) can not recognize TON of a telephone number as an international call, and “INT” is an indicator system, by which a mobile terminal or a mobile switching center can recognize TON of a telephone number as an international call.
FIG. 1 is a flow chart of a conventional call connecting method performed on an incoming number stored in a telephone directory of a mobile terminal.
Referring to FIG. 1, a user searches a telephone number stored in a memory of a mobile terminal or USIM (S101) and attempts to originate a call to a telephone number of a specific subscriber (S102), and a mobile switching center judges TON of the incoming number (S103).
In the case that the TON of the incoming number is checked as “Unknown” in the step S103, the mobile switching center interprets the incoming number and performs local call processing (S107), and in the case that the TON of the incoming number is checked as “INT”, the mobile switching center judges whether a country code (CC) of the incoming number is the same as a country code of a visited network (S104).
In case it is judged that the country code of the incoming number is not the same as a country code of a visited network in the step S104, the mobile switching center inserts an international PFX set therein before the incoming number, transmits IAM (Initial Address Message) to an international gateway MSC, and performs international call processing (S105 and S107).
Meanwhile, in the case that the country code of the incoming number is the same as a country code of a visited network, the mobile switching center transmits an SRI (Sending Routing Information) message to a home location register (HLR) or a gateway MSC of other service provider of the visited network, and performs call processing (S106 and S107).
However, in the case that, in a foreign country, a user uses a mobile terminal used in the home country by roaming, in some cases, the conventional call connecting method does not process a call made using a telephone directory. That is, a local telephone number stored in a telephone directory should be processed as an international call, however TON of a telephone number stored in the home country is generally set as “Unknown”, and thus the user can not make a call to a telephone number stored in the telephone directory in the international roaming mode.
Meanwhile, conventionally, in the case that the user stores telephone numbers belonging to a visited network into a telephone directory of a mobile terminal, the user should insert a country code of a visited network into each telephone number.